1. Field of the Invention
The present invention relates to alarm and sensor systems. More particularly, the present invention relates to a electrical circuit for use with doorways and gates which provides direction information to an alarm or announcer.
2. Description of the Prior Art
A variety of security devices have been employed at doorways and other ports which sound an alarm when activated by presence of an individual. An example of such an alarm is a sensor pad disposed under a door mat, the sensor in electrical communication with an announcer. The announcer is often in the form of a bell, horn, light, or other indicating signal. Another example of an alarm are infrared emitters and receivers spaced on either side of the port. When the IR signal is interrupted by an individual located between the emitter and the receiver, a signal is generated which activates an announcer. Although these and other prior art alarm measures are effective in sensing movement of an individual through a port, they do not indicate whether the individual is coming or going.
Oftentimes, the store owner, security guard, or other "employee" is alone at the workplace. In a situation where the employee enters a backroom for example, the activation of an announcer does not inform the employee whether a customer had just left, or a new customer(s) has just arrived. Unable to ascertain the presence of individuals from the announcer alone, the employee is subject to deception by a criminal. It would be highly desirable, therefore, to have an alarm system incorporating circuitry which can detect and announce the direction in which an individual is moving about the port or doorway.
Numerous innovations for alarm systems and circuitry have been provided in the prior an that are adapted to be used. Even though these innovations may be suitable for the specific individual purposes to which they address, they would not be suitable for the purposes of the present invention as heretofore described.